Also, I am one month in my six month challenge and have lost 10 of the 50 lbs I wagered on. It is definitely providing good additional motivation.
Just like anything else, it is up to you to set a realistic goal. (YOU are in complete control of the decision on how much to wager, what length of time you want to do it in, and how many pounds you plan to lose. If you fail at losing your chosen amount in the chosen time, it is not a failing of the company.) And, of course, don't bet more than you can afford to lose. If you do those things and commit to your program, you can be successful AND win some cash.
“The secret of health for both mind and body is not to mourn for the past, worry about the future, or anticipate troubles, but to live in the present moment wisely and earnestly.” ~ Buddha
"We cannot change the cards we are dealt, just how we play the hand." ~ Randy Pausch
"There's a difference between interest and commitment. When you're interested in doing something, you do it only when circumstance permit. When you're committed to something, you accept no excuses, only results." ~ Art Turock
"We have a saying in Tibet: If a problem can be solved, there is no use worrying about it. If it can't be solved, worrying will do no good." ~ 7 Years in T